Increase in capacity of a disk array system has advanced with recent increase in quantity of data used in an information processing system. The number of disk drives mounted in the disk array system has increased with the advance of increase in capacity of the disk array system.
On the other hand, greater reduction in size of the disk array system has been required for effective use of a limited installation space. Disk drives must be mounted densely in such a limited space because of the reduction in size. Therefore, a mechanism for performing maintenance of the disk array system efficiently, such as specification of a fault location or easy pursuit of the cause of an obstacle, need to be provided in the disk array system.